Primary causes of dementia include a number of neurological disorders, from the well-known Alzheimer’s disease to less familiar disorders, such as Pick’s disease. Primary causes of dementia usually cause irreversible memory loss and impaired thought processing.

Alzheimer’s Disease: Alzheimer’s disease is the most common form of dementia, and the disease most people associate with memory loss. A progressive disease with no current cure, Alzheimer’s disease is usually diagnosed after age 80, and is uncommon in people under the age of 65.

Although Alzheimer’s disease is irreversible, the progress of the disease can be slowed by medication.

Vascular Dementia: Vascular dementia occurs when small strokes or brain lesions impair blood flow to the brain. Vascular dementia is the cause of twenty percent of dementia cases, making it the second most common cause of dementia after Alzheimer’s disease.

Vascular dementia is also referred to as multi-infarct disease, or multiple stroke disease. Symptoms include memory loss, urinary incontinence, and muscle coordination problems. The typical vascular dementia patient is male, and over the age of fifty.

Symptoms of vascular dementia may appear suddenly, and then remain stable (or even show slight improvement) until the next set of strokes. Vascular disease is a progressive disease, worsening over time. It has also been linked to hypertension, and diabetes.

Pick’s Disease: Pick’s disease symptoms are often hard to distinguish from Alzheimer’s disease. Pick’s disease damages nerve cells in the brain’s frontal and temporal lobes. Nerve cells affected by Pick’s disease weaken and eventually die.

A sudden personality change is the main symptom of Pick’s disease, usually coupled with changes in social behavior. People between the ages of forty and sixty are most likely to develop Pick’s disease.

Lewy-Body Dementia: Lewy-body dementia may be related to Alzheimer’s disease. The cause of Lewy-body dementia is the presence of abnormal substances called Lewy-bodies in parts of the brain such as the cortex and brain stem. Lewy-body dementia causes classic dementia symptoms, including memory loss. The disease can also cause hallucinations, depression, and paranoia.

Normal-Pressure Hypocephalus: Normal pressure hypocephalus is caused by changes to brain structure that can be seen by neuroimaging tools. The disease causes memory loss, dementia, urinary incontinence, and an unusual gait.

Huntington’s Disease: Huntington’s disease is a genetically inherited neurological disease that can cause dementia. Huntington’s disease causes behavioral changes, and chorea (chorea is involuntary dance-like movements). The usual age of Huntington’s disease onset is between forty and sixty years old.

Parkinson’s Disease: Parkinson’s disease is a progressive neurological disease that affects movement and muscle control. Symptoms of Parkinson’s disease include tremors, balance problems, difficulty walking, and a rigid posture.

Parkinson’s disease destroys the brain’s nerve cells responsible for muscle control. Up to twenty percent of patients in advanced stages of Parkinson’s disease develop some degree of dementia.

Secondary Dementia Causes

Dementia-like symptoms can develop as a result of an underlying medical condition. If the underlying condition can be treated, the symptoms will generally improve. The following are some of the more common secondary causes that can lead to dementia.

Medication: As people age, they tend to require more medication for their health. Many of the medications include dementia symptoms as a side effect. The list of medications that cause dementia symptoms is incredibly long, and includes such common medications as:

  • anti-diarrhea medication
  • anti-epileptic medication
  • antihistamines
  • cold and flu medication
  • lithium
  • sleeping pills
  • tricyclic antidepressants.

Reducing the dose or switching to an alternative medication can often prevent dementia symptoms.

Alcohol Dementia and Substance Abuse: Alcohol abuse can lead to symptoms of dementia. The long-term toxic effects of alcohol on the brain are enough to cause dementia. Symptoms can often be improved by abstaining from alcohol.

Alcohol abuse increases the chances of head injuries, vitamin B1 deficiency, infections, and liver disease, all of which can cause dementia symptoms. Abuse of illegal drugs can also cause damage to the brain that results in dementia.

Vitamin Deficiency: A deficiency in vitamin E, the B vitamins, or folic acid may increase the chance of developing dementia. Current research is examining the relationship between vitamin deficiency and dementia symptoms. Eating a healthy diet may help prevent or reverse certain types of dementia. Of special interest to researchers is a possible link between vitamin deficiency and Alzheimer’s disease.

Infectious Diseases: A number of infections that affect the central nervous system have been known to cause dementia symptoms, including HIV, meningitis, and encephalitis.

  • Meningitis causes inflammation of the membranes surrounding the brain and spinal cord. Caused by viral, bacterial, or fungal agents, meningitis requires immediate medical attention. Meningitis should be ruled out when anyone develops sudden symptoms of dementia.
  • Encephalitis, like meningitis, can cause sudden dementia symptoms. Encephalitis is an inflammation of the brain itself, and can be caused by both bacterial and viral agents. Like meningitis, encephalitis is a serious illness that requires prompt medical attention.
  • Human immunodeficiency virus (HIV) can cause healthy brain cells to break down, releasing damaging enzymes. These enzymes then attack healthy neurons, causing dementia symptoms. Dementia is a common complication of HIV: Over twenty percent of HIV patients develop some symptoms of dementia. HIV clinical trials are testing medication that may block the neuron damaging action of the released enzymes.

Creutzfeldt-Jakob Disease: Creutzfeldt-Jakob disease is similar to “mad cow disease,” a progressive neurological disease that affects sheep and cows. Creutzfeldt-Jakob disease is the human version of mad cow disease.

Creutzfeldt-Jakob disease is an infectious disease that attacks brain tissue, leaving the tissue full of holes. The disease is fatal, and progresses rapidly. Creutzfeldt-Jakob disease begins with small changes to personality, and progresses into dementia symptoms that worsen over the course of several weeks.

Metabolic Disorders: Metabolic disorders can also cause symptoms of dementia. These disorders include:

  • cortisol hormone imbalances
  • diabetes
  • electrolyte levels (calcium and sodium imbalances)
  • kidney failure
  • liver disease
  • thyroid disorders.

Pseudodementia: Depression can result in dementia symptoms, including memory loss and a lack of motivation. Elderly people dealing with health problems, the loss of a spouse, or loneliness are particularly susceptible to depression. Treating the depression often results in the reversal of dementia symptoms.

Brain Tumors: Brain tumors put pressure on and damage the surrounding brain tissue. A brain tumor can cause a number of symptoms, including dementia. The tumor may originate in the brain, or may have spread to the brain from other organs.

This section provides additional information on a number of causes of dementia, including Pick’s disease and infectious diseases, with each listed in the menu to the left. To research other conditions that dementia causes or health issues, please use the more focus search tool.


Canadian Broadcasting Corporation. (updated 2003). Calgary team discovers how HIV may cause dementia.

Mayo Foundation for Medical Education and Research. (2003). Dementia: It’s not always Alzheimer’s.

National Institute on Aging. (2004, July). Forgetfulness: It’s not always what you think. The AgePage.

 Posted on : June 15, 2014